Aquarius was formed by The Boss under unknown circumstances. It began with a handful of Scorpia traitors - as well as The Boss himself - as a small criminal organization, taking on missions that mercinaries were just too expensive and inexpierenced to complete. Eventually, they began recruiting operators of their own, seemingly preferring ex-government employees and younger men.

When Aquarius is not trying to destory Scorpia (and Scorpia not trying to destroy Aquarius) they often work together.

Aquarius prides itself in being a secret organization. The intelligence services of the world did not think it existed until very recently, when they seemed to be targeting Alex Rider.